The present invention relates to the field of agricultural equipment, more particularly to agricultural machines, more particularly to agricultural machines that execute or integrate a function of spraying products over a distance, and has as its object an improved spraying device and an agricultural machine equipped with such device.
The devices concerned within the scope of the present invention are essentially of the type of device for spraying bulk or piecemeal products, in particular products for animal feed or formation of bedding for animals. Such devices generally comprise a casing in which a rotary spraying organ is mounted that is provided with a lateral ejection opening prolonged by a conduit or a spout, the said rotary organ having radial vanes designed to impel the products in order to eject them through the opening into the spout, by forming a material jet directed substantially along the median axis of the spout portion adjacent to the opening, and advantageously with simultaneous generation of a carrier air stream corresponding to the air stream generated by this rotary organ and sent into the spout. The ejection opening is made in the peripheral wall of the casing, along the internal face of which the outer ends of the radial vanes travel, and it is provided with a rim or bounding edge disposed on that side of the opening which is last to be reached by the outer peripheral ends of the vanes in the course of their rotation during operational functioning of the device, and which generally forms the lower rim or edge of the said opening.
Such devices are present on livestock feeding machines or shredding machines, which are autonomous, towed or mounted, but also on machines for distributing or moving products.
A particular application of this type of device concerns the distribution of products, such as hay or silage, to animals, or else for spraying straw onto their bedding.
Machines performing these functions are in particular sold by the Applicant in the scope of its PRIMOR product line.
These machines are generally provided with a chamber in which the products to be sprayed are loaded (often in partly agglomerated or compacted form, such as bales, bunches, blocks or the like), to be conveyed, for example by a beater drum, into the casing containing the rotary spraying organ (or turbine).
In this way these products arrive on the radial distribution vanes of the rotating turbine, are impelled by them in their rotary movement and are ejected from the casing via the peripheral lateral opening under the effect of centrifugal force (and therefore of the movement imparted thereby) and of the air stream generated by the rotation of the vanes and channeled through the opening and the attached spout. By way of example, the document EP 1149527 describes such a machine.
Typically, the rotary spraying organ (turbine) can have a speed of rotation on the order of 620 rpm when the machine is used to execute a shredding operation, the straw being sprayed for a distance of between 5 and 18 m. In contrast, the machine has a speed of rotation of only 310 rpm when the machine is being used to execute a distribution operation in which the products loaded into the chamber must be deposited at the foot of the machine (examples of the most commonly treated products: hay, corn silage, grass silage, wrapped grass).
On certain machines used to execute the operations of shredding and distribution, a supplementary function of chopping exists. Thus the product in the form of long-stalked vegetation can be chopped and therefore shortened before being ejected.
Usually the straw is a dry product, since it is stored in a shed or the like. The straw introduced into the chamber arrives on the radial distribution vanes of the turbine and is chopped by the cutters and counter-cutters disposed on the circumference. When the straw stalks are sufficiently short and light, they are ejected by the main air stream created by the turbine. The insufficiently chopped stalks are recycled, in other words they fall between the cutters and the recycling plate so as to be passed once again into the casing.
Such a distributing shredder-chopper as described, for example, in FR 2993138) is now functioning effectively with dry products. In contrast, problems arise when the product to be distributed is wet, in particular because the position of the adjustable counter-cutter, at the level of the orifice of the lateral outlet, obstructs and/or diverts the product.
In effect, the heavier product tends to be too low relative to the main stream and it does not have enough velocity to be ejected: it therefore accumulates at the level of the recycling zone.
Furthermore, the product that is ejected but not transported in the main stream is not sprayed sufficiently far away (sometimes to a distance of less than 5 meters) and, for example, may be end up at the level of the feed alley.
This problem is also encountered, on a smaller scale, on the machines used for shredding and distribution without being equipped with the chopping function.
In the case of a machine equipped with the chopping function, the accumulation of the wet product at the level of the recycling zone may be enough to cause blockages.
For example, the wet long-stalked vegetation is taken from a bale of fodder that is wrapped in a tight envelope formed by interlaced tapes of plastic material. This fodder contains approximately 45-50% of dry matter. The distribution of the product originating from a wrapped bale takes place in packets, because the long stalks are entangled. To facilitate the passage of the packets, the cross section of the outlet orifice may be made larger. Despite this larger cross section, however, the risk of blockage related to the accumulation of product on the lower rim or edge of the ejection opening (folded-over portion of the upper end 54 of the recycling plate 52 of the document FR 2993138) remains.
In the region of this lower rim and to some extent in the lower part (one fifth to one third of its height) of the attached passage formed by the spout portion adjacent to the opening, the inventors have identified a neutral zone, of weak flow or of turbulent flow, which is not crossed by the main air stream. In effect, it has been possible to observe that the main stream is concentrated in the upper part of the ejection orifice and of the interior passage of the spout.
In this neutral zone, the speed of the blower is too low to eject the wet stalks, which are heavier, and they therefore fall due to gravity and accumulate on the said rim and entry of the spout. This problem is accentuated in the presence of a counter-cutter in the upper part close to the opening, and especially when this counter-cutter is completely outside in order to achieve intensive chopping.
This problem is also present when it is desired to spray wet straw, stored outside, onto the bedding. The heaviest stalks end up and become accumulated in the neutral zone, in other words at the level of the lower rim and of the entry of the spout. The wetness further accentuates the phenomenon of adherence of the stalks to one another.
From documents EP 1149527 and EP0098769, agricultural machines for distribution of products are further known in which a turbine performing a spraying function and a chopping function is mounted in the ejection spout. The passage into the spout is consequently almost totally obstructed by the turbine, and the quantity of products that can be sprayed as well as the spraying distance is therefore greatly limited by this fact.